21406271 has 2 divisors, whose sum is σ = 21406272. Its totient is φ = 21406270.

The previous prime is 21406249. The next prime is 21406279. The reversal of 21406271 is 17260412.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21406271 - 2⁶ = 21406207 is a prime.

It is a Sophie Germain prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21406279) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10703135 + 10703136.

It is an arithmetic number, because the mean of its divisors is an integer number (10703136).

Almost surely, 2^21406271 is an apocalyptic number.

21406271 is a deficient number, since it is larger than the sum of its proper divisors (1).

21406271 is an equidigital number, since it uses as much as digits as its factorization.

21406271 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 672, while the sum is 23.

The square root of 21406271 is about 4626.6911502714. The cubic root of 21406271 is about 277.6602261660.

Adding to 21406271 its reverse (17260412), we get a palindrome (38666683).

The spelling of 21406271 in words is "twenty-one million, four hundred six thousand, two hundred seventy-one".